Fuel vaporizing combustion apparatus for turbojet



Oct. 11, 1955 H. w. TUTHERLY FUEL VAPORIZING COMBUSTION APPARATUS FOR TURBOJET Filed May 29, 1950 INVENTOR HE RBERT W. TUTHERLY BY R W ATTORNEY ll Ill Illllllll United States Patent FUEL VAPORIZIN G COMBUSTION APPARATU FOR TURBOJET Herbert W. Tutherly, Media, Pa., assignor, by mesne assignments, to the United States of America as representedby theSecretary of the Navy Application May 29, 1950, Serial No. 165,063

4 Claims. (Cl. 6039.65)

development of hot spots. It is an object of the present invention to provide improved combustion apparatus constructed and arranged to obviate such difficulties in obtaining efficient release of energy from fluid fuel.

Features of the invention include the mounting of hood structure in spaced relation with respect to the forward or ignition end of a combustion chamber, to provide pre heating passages through which a mixture of primary air and fuel is conducted prior to introduction into the combustion zone.

It is another object of the invention to provide means for effecting transfer of heat from the zone of combustion to a mixture of fuel and primary air, the fuel-air ratio of which may initially be too rich to burn, and means for supplying the heated mixture to the combustion zone along with sutficient additional primary air to facilitate ignition, and ensure complete combustion in the presence of secondary air throughout the full length of the zone.

A further object of the invention is the provision of improved combustion apparatus facilitating complete vaporization and combustion of liquid fuel, and minimizing the deposition and burning of fuel on combustor walls and consequent accumulation thereon of carbon.

These and other objects are effected by the invention as will be apparent from the following description and claims. taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a diagrammatic longitudinal view, partly in section, of an aviation turbojet power plant equipped with combustion apparatus constructed in accordance with a preferred form of the invention;

Fig. 2 is an enlarged detail, sectional view of a portion of the combustion apparatus shown in Fig. 1; and

Fig. 3 is a fragmentary sectional view taken along the line IIIIII of Fig. 2.

The essential elements of the typical aviation gas turbine power plant illustrated diagrammatically in Fig. 1 include an outer casing structure 11, comprising a number of cylindrical sections and having mounted therein an inner sectional core structure 12 to form an annular flow passageway 13, which extends longitudinally through the engine from a forwardly-directed intake opening 14 to a rearwardly-disposed discharge nozzle 15. It will be understood that the casing structure 11 is adapted to be mounted in or on the fuselage or wing of an aircraft,

with the inlet opening 14 pointed forwardly. Operating 2,720,081 Patented Oct. 11, 1955 elements of the gas turbine engine are arranged in axial alignment in order to minimize the frontal area presented by the engine, and include an axial-flow compressor 19, combustion apparatus generally indicated. at 20 illustrated in annular form, and a turbine 21, which is operatively connected to the rotor of the compressor through the medium of an axially disposed shaft 22.

In accordance with well-known principles of operation of gas turbine power plants, air entering the annular intakeopening 14 passes to the compressor 19, which delivers the air under pressure through the passage 13 to the combustion apparatus 20 for supporting combustion of fuel, which may be admitted by means hereinafter described. Heated motive fluid thus generated in the combustion apparatus 20 is. then expanded through the turbine 21 for driving the compressor, while the exhausted motive fluid is discharged to the atmosphere by way of the nozzle 15, usually in the form of a propulsive jet.

The combustion apparatus 20 embodying the invention is preferably annular in form, although the features of the invention are readily adapted to be employed in combustion apparatus of the multiple unit or can type. According to the invention in the form illustrated in Fig. 2, the combustion apparatus comprises a burner structure having outer and inner sectional annular walls25 and 26, which form a generally diverging combustion chamber 27. The outer wall 25 may consist of an assembly of overlapped sections or rings, including a forward section 29, while the inner wall 26 may likewise constitute an assembly including a forward section 30, which is disposed within the outer section 29. Suitable inlets 33 for secondary air may be formed in the walls 25 and 26, and additional annular inlets 34 are also provided by means of spacers interposed between the overlapping portions of the assembled sections. The forward wall sections 29 and 30 are supported on radially disposed struts 35 extending between the inner and outer casings 12 and 11.

According to the invention, imperforate upstream portions 31 and 32 of the forwardly disposed wall sections 29 and 30 are inswept and joined to the apertured portions thereof by radially offset flange portions 31a and 32a, respectively, to form a relatively narrow annular ignition zone 27a of the combustion chamber having an annular entryway 36 which is formed between the terminal flanges of the sections. Annular outer and inner hood sections 37 and 38 are supported on the struts 35 outwardly and inwardly of the respective upstream portions 31 and 32. of the burner wall sections 29 and 30, forming outer and inner annular preheating ducts or passages 40 and 41. The preheating passage 40 has a lateral annular inlet 42, communicating with the passageway 13 adjacent the flange portion 31a, and an annular outlet 43 communicating with the entryway 36 for the ignition zone. Similarly, the preheating passage 41 communicates through an annular inlet 44 with the passageway 13, and discharges into the entryway 36 by way of an annular opening 45. An annular auxiliary air supply opening 46 is formed between the aligned forward edges of the hood sections 37 and 38 in advance or upstream of the confluence of the preheating duct outlets 43 and 45, and entryway 36.

It will be understood that the passage volumes between the outer casings and the combustor are sufficiently reduced by reason of the relatively larger diameter of the second burner wall section 29 to insure the desiredflow of air into the combustor through the vaporizing passages 4i) and 41. In other words, flanges 31a and 32a are designed to extend away from portions 31 and 32 by an amount which will result in wall sections 29 and 30 being to cause positive flow through passages 40 and 41 in the desired direction.

For supplying fluid fuel to the combustion apparatus 20, annular fuel manifolds 48 and 49 are mounted adjacent the flange portions 31a and 32a and within the preheating duct inlets 42 and 44, and are provided with suitable nozzle openings for spraying fuel forwardly into the respective preheating ducts 40 and 41. Fuel under pressure may be supplied to the manifolds by way of conduits 50 and suitable control valve apparatus (not shown). It will be understood that suitable ignition means (not shown) may also be associated with the combustion apparatus to start the combustion process in the usual well-known manner.

ing through the preheating ducts 40 and 41, producing an air-fuel ratio which is initially too rich to burn. As the heated air and fuel mixture flows from the preheating ducts through the entryway 36 into the ignition zone 27a, however, additional primary air is introduced by way of the auxiliary supply opening 46 in quantities sufficient to support combustion. The full length of the combustion chamber 27 is then available for complete combustion of fuel thus ignited within the ignition zone 27a, secondary air being supplied by way of the apertures 33 and 34.

From the foregoing it will thus be seen that an improved combustion apparatus constructed in accordance with the invention will be operative to effect adequate vaporization and mixture of the fuel with primary air, efiicient preheating of the mixture without cracking of the fuel, and complete combustion within the combustion chamber without incidental depositing of carbon on the burner walls.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

l. Combustion apparatus for a power plant having cylindrical casing structure forming an annular air passageway, said combustion apparatus comprising outer and inner annular apertured shell structures spaced between the walls of said passageway and enclosing a combustion chamber, spaced outer and inner annular imperforate wall portions carried on the upstream ends of said shell structures, respectively, for defining a relatively narrow upstream ignition zone of said combustion chamber and having an annular entryway, outer and inner annular hood sections mounted in spaced relation on opposite sides of the respective wall portions and having flanges converging in advance thereof to define an annular primary air passage aligned upstream of the entryway to said ignition zone, said hood sections and wall portions being spaced apart to form outer and inner annular mixing ducts having lateral inlets and extending upstream therefrom along the respective wall portions into communication with said primary air passage and said entryway to the ignition zone, and fuel supply means mountcd air supply passage, combustion apparatus mounted in said passage and comprising diverging shell structure having a primary air entryway formed in the upstream end thereof and a plurality of secondary air inlets formed in downstream portions thereof, said shell structure including an imperforate ignition portion between said primary air entryway and said secondary air inlets, hood structure telescoping and spaced from said advance section of the wall structure for forming a preheating duct contiguous thereto, said preheating duct having a lateral inlet communicating with said supply passage and an outlet communicating with said primary air entryway, fuel supply means for spraying fuel into the stream of primary air flowing into said inlet of said preheating duct, and an auxiliary primary air passage formed in said hood structure in alignment with said primary air entryway in the wall structure for effecting confluence 0f the relatively rich fuel and air mixture from said preheating duct with sufficient primary air from said auxiliary passage to support combustion in said ignition portion of the combustion apparatus.

3. In a gas turbine power plant having an annular axial-flow air supply passage, annular combustion apparatus mounted in said air supply passage and comprising annular shell structure having diverging walls forming an annular primary air entryway in the upstream end thereof, said walls having a plurality of secondary air inlets formed in the downstream portions thereof, said walls including parallel imperforate upstream portions between said entryway and said inlets forming an annular ignition space communicating with said entryway, inner and outer annular hood members cooperating to telescope said upstream portions for forming annular inner and outer preheating ducts contiguous to said Walls on both sides of said ignition space, said preheating ducts having lateral annular inlets communicating with said air supply passage and annular outlets open adjacent said entryway to the ignition space, and annular fuel spraying manifolds mounted adjacent the inlets of said preheating ducts for introducing fuel into the primary air flowing through said ducts toward said entryway of the shell structure.

4. In a gas turbine power plant having an annular axial-flow air supply passage, annular combustion apparatus mounted in said air supply passage and comprising annular shell structure having diverging walls forming an annular primary air entryway in the upstream end thereof, said walls having a plurality of secondary air inlets formed in the downstream portions thereof, said walls including parallel imperforate upstream portions between said entryway and said inlets forming an annular ignition space communicating with said entryway, inner and outer annular hood members cooperating to telescope said upstream portions for forming annular inner and outer preheating ducts contiguous to said walls on both sides of said ignition space, said preheating ducts having lateral annular inlets communicating with said air supply passages and outlets open adjacent said entryway to the ignition space, and annular fuel spraying manifolds mounted adjacent the inlets of said preheating ducts for introducing fuel into the primary air flowing therethrough, said hood members being radially spaced apart to provide an annular aperture in alignment with the confluence of said preheating ducts and said entryway of the shell structure, whereby additional primary air is supplied to the air and fuel mixture entering said combustion apparatus.

References Cited in the file of this patent UNITED STATES PATENTS 2,443,707 Korsgren June 22, 1948 2,448,561 Way Sept. 7, 1948 2,510,645 McMahan June 6, 1950 2,552,851 Gist May 15, 1951 

